Come-off prevention structure of annular component

Abstract

To provide a come-off prevention structure of an annular component capable of suppressing increase in cost and labor while improving come-off prevention force of the annular component against a rotor.SOLUTION: A come-off prevention structure is configured such that a snap ring 8 is fitted and fixed in place in an annular groove 1d formed on an outer peripheral surface of a rotational shaft 1 (a rotor that rotates around a central axis O), and is axially engageable with an inner ring 4 (annular part) of a rolling bearing 3 mounted on the outer periphery of the rotational shaft 1, thereby preventing the inner ring 4 from coming off from the rotational shaft 1. In the come-off prevention structure, a restriction protrusion part 7 provided integrally with the inner ring 4 is arranged radially outward of the snap ring 8, thereby restricting radial expansion and deformation of the snap ring 8.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a retaining structure for an annular part attached to the outer periphery of a rotating body. [Background technology]

[0002] In order to axially position an annular component attached to the outer periphery of a rotating body that can rotate around a central axis (to prevent the annular component from slipping off relative to the rotating body), a retaining structure may be employed in which a retaining ring (shaft retaining ring) that can be engaged with the annular component in the axial direction is fitted and fixed into an annular groove formed on the outer periphery of the rotating body. Such a retaining structure is employed, for example, when attaching a bearing as an annular component to a rotating shaft as a rotating body, as described in Patent Document 1 below, and in this case, a C-type retaining ring (C-type eccentric retaining ring, C-type concentric retaining ring) or an E-type retaining ring specified in JIS B 2804 is generally used as the retaining ring.

[0003] In Patent Document 1, an annular retaining member is additionally disposed axially outside the retaining ring and fixed to the rotating shaft, and the retaining member is provided with a visor portion whose inner peripheral surface abuts or closely faces the outer peripheral surface of the retaining ring. In this way, even if the retaining ring attempts to expand in diameter due to centrifugal force acting on the retaining ring as the rotating shaft rotates (high-speed rotation), the visor portion of the retaining member can suppress this expansion, thereby reliably preventing the retaining ring from coming out of the annular groove. The retaining member is fixed to a predetermined axial position on the rotating shaft by threading a female thread formed on its inner peripheral surface into a male thread formed on the outer peripheral surface of the rotating shaft, or by fixing a separate nut member to the end of the rotating shaft. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2004-68845 Summary of the Invention [Problem to be solved by the invention]

[0005] The technical means described in Patent Document 1 can increase the force with which the retaining ring is held against the rotating shaft, thereby increasing the force with which the annular part is held against the rotating shaft. However, this requires additional work and cost because a separate part other than the retaining ring must be fixed to the rotating shaft.

[0006] In view of this situation, the present invention aims to provide a structure for preventing the annular part from coming loose, which has a simpler structure and improves the force of preventing the annular part from coming loose from the rotating body, while suppressing increases in cost and effort. [Means for solving the problem]

[0007] The present invention, which has been invented to achieve the above object, provides a retaining structure for an annular component that prevents the annular component from coming off from the rotating body by fitting and fixing a retaining ring that is axially engageable with the annular component attached to the outer periphery of the rotating body into an annular groove formed on the outer periphery of the rotating body that rotates around a central axis, the retaining ring comprising: The restricting projection formed integrally with the annular component is disposed radially outward of the retaining ring, thereby restricting the radial expansion and deformation of the retaining ring.

[0008] As described above, in the present invention, by arranging the restricting protrusion integrally formed on the annular component itself that is attached to the outer periphery of the rotating body, on the radially outer side of the retaining ring, it is possible to restrict the radial expansion and deformation of the retaining ring, as well as the removal of the retaining ring from the rotating shaft that results from this radial expansion and deformation, and further the removal of the annular component itself. Although the configuration of the present invention in which the restricting protrusion is (additionally) provided on the annular component may result in a slight increase in cost of the annular component, no additional components other than the retaining ring are required to improve the retention force of the annular component against the rotating body, and therefore increases in cost and effort can be significantly reduced compared to conventional configurations.

[0009] In the above configuration, the restricting protrusion may be an annular portion that is continuous in the circumferential direction, or a plurality of restricting protrusions may be provided at intervals in the circumferential direction.

[0010] In the above configuration, the restricting protrusion can be provided on the inner ring of a bearing (the inner ring of a rolling bearing) as the annular component. That is, the retaining structure for an annular component according to the present invention can be preferably applied, for example, to retaining a rolling bearing that rotatably supports a rotating body from coming off the rotating body. [Effects of the Invention]

[0011] As described above, according to the present invention, it is possible to provide a structure for preventing a ring-shaped part from coming off, which has a simpler structure and improves the force of preventing the ring-shaped part from coming off relative to a rotating body that can rotate around a central axis, while suppressing increases in cost and effort. [Brief explanation of the drawings]

[0012] [Figure 1] 1 is a vertical cross-sectional view conceptually showing a support structure for a rotating shaft to which a retaining structure according to an embodiment of the present invention is applied. [Figure 2] 2A to 2C are diagrams illustrating a method of attaching a retaining ring when forming the retaining structure shown in FIG. 1. [Figure 3] FIG. 2 is a schematic cross-sectional view taken along the line AA in FIG. [Figure 4] FIG. 10 is a cross-sectional view of a support structure for a rotating shaft to which a retaining structure according to another embodiment of the present invention is applied. [Figure 5] FIG. 10 is a cross-sectional view of a support structure for a rotating shaft to which a retaining structure according to another embodiment of the present invention is applied. [Figure 6] 1 is a schematic diagram of a rotary shaft type ball screw device employing a retaining structure according to the present invention. [Figure 7] 1 is a schematic diagram of a nut-rotating type ball screw device employing a retaining structure according to the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0013] Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

[0014] FIG. 1 is a longitudinal cross-sectional view conceptually illustrating a support structure for a rotating shaft 1 to which a retaining structure for an annular component according to an embodiment of the present invention is applied. This support structure comprises the rotating shaft 1 as a "rotating body" rotatable about a central axis O, and a rolling bearing 3 attached to the outer periphery of the rotating shaft 1 and supporting the rotating shaft 1 rotatably relative to a housing 2, and the rotating shaft 1 is capable of rotating at high speeds of several thousand rpm or more. In the following description, the "axial direction" refers to the direction along the central axis O of the rotating shaft 1 (rotating body). Furthermore, the "radial direction" refers to the radial direction of a circle centered on the central axis O, and the "circumferential direction" refers to the circumferential direction of a circle centered on the central axis O.

[0015] The rotating shaft 1 is a stepped shaft having a small-diameter outer peripheral surface 1a that is cylindrical and has a constant diameter, a large-diameter outer peripheral surface 1b that is larger than the small-diameter outer peripheral surface 1a, and a shoulder surface 1c that extends radially and connects the outer peripheral surfaces 1a and 1b. The housing 2 has an inner peripheral surface 2a that is cylindrical and has a constant diameter, and a shoulder surface 2b that extends radially.

[0016] The rolling bearing 3 includes an annular inner ring 4 and an outer ring 5, a plurality of rolling elements (balls in this case) 6 interposed between the inner and outer rings 4, 5, and a cage (not shown) that holds the plurality of balls 6 at intervals in the circumferential direction. The rolling bearing 3 is mounted on the rotating shaft 1 with one end face (the end face on one axial side) of the inner ring 4 abutting against a shoulder surface 1c of the rotating shaft 1 and one end face of the outer ring 5 abutting against a shoulder surface 2c of the housing 2.

[0017] An annular groove 1d is formed in the small-diameter outer peripheral surface 1a of the rotating shaft 1, and a retaining ring 8 is fitted into this annular groove 1d so as to be axially engageable with the other end face (the end face on the other axial side) of the inner ring 4. As a result, the inner ring 4, which is the "annular component" referred to in the present invention, is prevented from coming off relative to the rotating shaft 1 and is positioned in the axial direction. An annular groove 2b is formed in the inner peripheral surface 2a of the housing 2, and a retaining ring 9 is fitted into this annular groove 2b so as to be axially engageable with the other end face of the outer ring 5. As a result, the outer ring 5 is prevented from coming off relative to the housing 2 and is positioned in the axial direction. The retaining ring 8 may be fitted into the annular groove 1d of the rotating shaft 1 so as to be detachable from it, and the retaining ring 9 may be fitted into the annular groove 2b of the housing 2 so as to be detachable from it. In this way, if the retaining rings 8, 9 are detachable from the annular grooves 1d, 2b, the workability of maintenance work, such as repairing or replacing the rolling bearing 3, is significantly improved.

[0018] The retaining ring 8 fitted to the rotating shaft 1 has a circumferential slit in consideration of ease of attachment to the rotating shaft 1, and here a C-type retaining ring specified in JIS B 2804 is used (see FIG. 3). In this case, if centrifugal force acts on the retaining ring 8 as the rotating shaft 1 rotates, the diameter of the retaining ring 8 expands so that the slit widens in the circumferential direction, which may cause the retaining ring 8 to come off the annular groove 1d. In particular, in this embodiment, in which the rotating shaft 1 may rotate at high speeds exceeding several thousand rpm, a large centrifugal force acts on the retaining ring 8 as the rotating shaft 1 rotates, increasing the possibility that the diameter of the retaining ring 8 will expand and deform.

[0019] Therefore, in this embodiment, a restricting protrusion 7 is integrally provided on the inner ring 4 as an annular component, and is disposed adjacent to (or close to) the radially outer side of the retaining ring 8, and this restricting protrusion 7 restricts the radial expansion deformation of the retaining ring 8. This makes it possible to restrict the radial expansion deformation of the retaining ring 8 and the displacement of the retaining ring 8 and the inner ring 4 relative to the rotating shaft 1 (the annular groove 1d provided therein) that results from this radial expansion deformation. Although the configuration of this embodiment in which the restricting protrusion 7 is (additionally) provided on the inner ring 4 may result in a slight increase in cost for the inner ring 4 (and the rolling bearing 3 including the inner ring 4), no additional parts other than the retaining ring 8 are required to improve the force with which the inner ring 4 is prevented from coming off the rotating shaft 1, and therefore increases in cost and effort can be significantly reduced compared to the conventional configuration described in Patent Document 1.

[0020] Because the restricting protrusion 7 is provided integrally with the inner ring 4, when fitting the retaining ring 8 into the annular groove 1d of the rotating shaft 1, the retaining ring 8 needs to be accommodated in a retaining ring accommodating space 10 formed between the annular groove 1d and the restricting protrusion 7 of the inner ring 4, as shown in Fig. 2. At this time, as shown in Fig. 2, the retaining ring 8 is elastically deformed into a dish shape with the inner diameter side end positioned to one side in the axial direction than the outer diameter side end, and after the inner diameter side end is fitted into the annular groove 1d, the outer diameter side end is fitted into the radially inner side of the restricting protrusion 7. This allows the retaining ring 8 to be smoothly installed in the retaining ring accommodating space 10.

[0021] To ensure good fit of the retaining ring 8 in the annular groove 1d of the rotating shaft 1 (good attachment of the retaining ring 8 to the retaining ring receiving space 10), the retaining ring 8 is designed to have a thickness (axial dimension) t that is smaller than the groove width t1 of the annular groove 1d. However, in this case, the retaining ring 8 fitted in the annular groove 1d can easily come off from the annular groove 1d unless some countermeasure is taken. Therefore, in this embodiment, the inner ring 4 provided with the restricting protrusion 7 is used to prevent the retaining ring 8 fitted in the annular groove 1d from coming off. Specifically, as shown in FIG. 2 , the opposing surface 4a of the inner ring 4 that faces the retaining ring 8 fitted in the annular groove 1d in the axial direction is positioned within the axial range of the annular groove 1d (positioned between a pair of inner wall surfaces 1da and 1db that define the groove width t1 of the annular groove 1d), allowing the retaining ring 8 to be clamped in the axial direction between the opposing surface 4a of the inner ring 4 and the inner wall surface 1db of the annular groove 1d. This improves the ease of mounting the retaining ring 8 in the retaining ring accommodating space 10, while making it difficult for the retaining ring 8 to come off the annular groove 1d.

[0022] In addition, in order to prevent the retaining ring 8 fitted into the annular groove 1d of the rotating shaft 1 from coming off, the retaining ring 8 used has a radial dimension x that is larger than the radial dimension x1 between the small-diameter outer surface 1a of the rotating shaft 1 and the inner diameter surface 7a of the regulating protrusion 7 provided on the inner ring 4 (x>x1).

[0023] The restricting protrusion 7 may be a continuous annular portion in the circumferential direction as shown in Fig. 3, or may be a plurality of restricting protrusions 7 provided at intervals in the circumferential direction as shown in Fig. 4. Fig. 4 shows a case where three arc-shaped restricting protrusions 7 are arranged at equal intervals in the circumferential direction.

[0024] As the retaining ring 8 that prevents the inner ring 4 from coming off, in addition to a C-type retaining ring as conceptually shown in Figures 3 and 4, an E-type retaining ring as conceptually shown in Figure 5 can also be used. C-type retaining rings include "concentric retaining rings" in which the centers of the inner and outer peripheral surfaces are aligned as shown in Figures 3 and 4, as well as "eccentric retaining rings" in which the center of the outer peripheral surface is eccentric relative to the center of the inner peripheral surface. However, because the mass around the rotating shaft 1 is not uniformly distributed, eccentric retaining rings are more likely than concentric retaining rings to cause problems such as radial expansion deformation and detachment from the annular groove 1d when the rotating shaft 1 rotates. For this reason, when using a C-type retaining ring, it is preferable to use a concentric retaining ring as shown in Figures 3 and 4.

[0025] The retaining structure according to the embodiment of the present invention described above can be applied to, for example, a ball screw device as conceptually shown in each of FIGS.

[0026] 6 is a so-called axially rotating ball screw device that includes a screw shaft 11 as a rotating shaft 1 (rotating body) with a spiral external thread groove 11a formed on its outer circumferential surface, a nut 12 with a spiral internal thread groove 12a formed on its inner circumferential surface, and a plurality of balls 13 that are arranged between the external thread groove 11a of the screw shaft 11 and the internal thread groove 12a of the nut 12 and transmit torque between the screw shaft 11 and the nut 12. In this ball screw device, a drive gear 14 is fixed to the screw shaft 11 using a key 15 so as to be rotatable together with the screw shaft 11, and when the drive gear 14 and the screw shaft 11 rotate together upon receiving output from a rotary drive source (not shown), the nut 12 moves back and forth in the axial direction.

[0027] In this embodiment, a retaining structure according to an embodiment of the present invention is employed to prevent the inner ring 4 of the rolling bearing 3, which rotatably supports the screw shaft 11 as a rotating body, from coming off relative to the screw shaft 11. That is, a retaining ring 8 is fitted and fixed in an annular groove formed on the outer circumferential surface of the screw shaft 11, and this retaining ring 8 prevents the inner ring 4 as an annular part from coming off relative to the screw shaft 11. A restricting protrusion 7 is formed integrally with the inner ring 7, and by arranging this restricting protrusion 7 radially outward of the retaining ring 8, radial expansion and deformation of the retaining ring 8 due to rotation of the screw shaft 11 is restricted.

[0028] 7 is a so-called nut-rotating ball screw device that includes a screw shaft 11 having a helical external thread groove 11a formed on its outer circumferential surface, a nut 12 as a rotating body having a helical internal thread groove 12a formed on its inner circumferential surface, and a plurality of balls 13 that are arranged between the external thread groove 11a of the screw shaft 11 and the internal thread groove 12a of the nut 12 and transmit torque between the screw shaft 11 and the nut 12. In this ball screw device, a drive gear 14 is fixed to the nut 12 using a key 15 so as to be rotatable together, and when the drive gear 14 and the nut 12 rotate together upon receiving output from a rotary drive source (not shown), the screw shaft 11 moves back and forth in the axial direction.

[0029] In this embodiment, a retaining structure according to an embodiment of the present invention is employed to prevent the inner ring 4 of the rolling bearing 3, which rotatably supports the nut 12 as a rotating body relative to the housing 2, from coming off the nut 12. That is, a retaining ring 8 is fitted and fixed in an annular groove formed in the outer peripheral surface of the nut 12, and this retaining ring 8 prevents the inner ring 4 as an annular part from coming off the nut 12. A restricting protrusion 7 is formed integrally with the inner ring 7, and by arranging this restricting protrusion 7 radially outward of the retaining ring 8, expansion and deformation of the retaining ring 8 as the nut 12 rotates is restricted.

[0030] The above describes the anti-slip structure according to an embodiment of the present invention, but the embodiment of the present invention is not limited to this, and appropriate modifications can be made within the scope that does not deviate from the gist of the present invention.

[0031] For example, in the above, the anti-slip structure of the present invention has been applied to preventing the inner ring 4 of the rolling bearing 3 from coming off from a rotating body (rotating shaft 1, screw shaft 11 or nut 12), but the present invention can naturally also be applied to preventing annular parts other than the inner ring 4 of the rolling bearing 3 from coming off from a rotating body. [Explanation of symbols]

[0032] 1 Rotation axis (rotating body) 1d Annular groove 2. Housing 3. Rolling bearings 4 Inner ring (annular part) 7 Regulating protrusion 8 Retaining ring O center axis

Claims

1. A retaining structure for an annular component, in which a retaining ring is fitted and fixed in an annular groove formed on the outer circumferential surface of a rotating body that rotates around a central axis, so as to prevent the annular component from coming off the rotating body, the retaining ring being engageable with the annular component attached to the outer periphery of the rotating body in the axial direction, A structure for preventing the retaining ring from coming loose, characterized in that the restricting protrusion formed integrally with the annular part is positioned radially outside the retaining ring, thereby restricting the radial expansion and deformation of the retaining ring.

2. 2. The structure for preventing slip-out of an annular part according to claim 1, wherein the restricting protrusion has a circular ring shape that is continuous in the circumferential direction.

3. The structure for preventing slip-out of an annular part according to claim 1 , wherein a plurality of the restricting protrusions are provided at intervals in the circumferential direction.

4. 4. The structure for preventing the annular component from coming off according to claim 1, wherein the restricting protrusion is provided on an inner ring of a bearing as the annular component.

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